ZooL.— Vol. III.] STEVENS— CILI ATE INFUSORIA. 15 



breadth (figs. 22 to 27) and becomes somewhat shorter 

 (figs. 24 to 26). Indentations appear in the attachment 

 disc and at the posterior end of the oral disc; these division 

 lines extend until the individuals separate, the last con- 

 necting bond being the velum. The two attachment discs 

 are at first separated by a double line of short cilia (fig. 

 13, u), an ingrowth of the inner row of cilia of the original 

 disc. Successively the other circles of cilia and the velum 

 of each cup are completed and the individuals separate. 



Micronucleus. (?) — This body increases in diameter from 

 2 )i4 to 3 ytt, becomes less stainable and therefore more diffi- 

 cult to follow. It moves down the neck and assumes the 

 positions shown in figs. 21 to 23. In the stage shown 

 in fig. 24, two such bodies were found in sections, but 

 division has thus far eluded observation. It is to be 

 hoped that future work on the infusorian may give the in- 

 termediate stages, and the changes in position of the two 

 bodies in stages between those shown in figs. 24 and 27. 

 In the specimen figured in 27 from an in toto preparation of 

 fresh material stained with alum carmine, both micronuclei 

 (?) were distinctly seen below their respective cups, and in 

 sections of young LicnophorcB they are always found in 

 normal position immediately under the attachment cup, and 

 to the left of the axial neck fibre. 



Macronuclei. — In the earliest stage of division seen (fig. 

 18), the macronuclei are distinct and unchanged in posi- 

 tion, but very soon they begin to unite, usually in pairs, 

 as described by Wallengren, but frequently three united 

 and odd ones are left here and there (fig. 19). The 

 pairs unite with one another irregularly, with a tendency to 

 accumulate on the right side of the animal (figs. 20 and 

 21). The whole macronuclear substance now becomes 

 concentrated into from one to six rounded masses located 

 within the peristomal region (fig. 22). These masses show 

 indications of a skein stage, but are very dense and stain 

 deeply. The nuclear masses now lengthen out transversely 

 in dumb-bell form and extend nearly across the broad body 



